This specification relates to combining search results from different search engine systems.
Internet search engines provide information about Internet accessible resources (e.g., web pages, images, text documents, multimedia content) that are responsive to a user's search query by returning a set of search results in response to the query. A search result includes, for example, a Uniform Resource Locator (URL) for the resource and a snippet of information. The search results can be ranked according to scores assigned to them by a scoring function. The scoring function scores the search results according to various signals, for example, where (and how often) query terms appear in the search results and how common the query terms are in the search results indexed by the search engine.